The objectives of this proposal are two-fold. Firstly, we intend to acquire a precise knowledge of the structure and the dynamic state of membrane components of normal erythrocytes, especially of membrane proteins which have functional significance and of their interaction with other membrane components, intracellular substances, drugs and metabolites by magnetic resonance spectroscopies. Secondly, erythrocyte membrane proteins from hereditary spherocytosis (HS) patients will be studied in a similar manner in an attempt to reveal the intrinsic molecular abnormality of HS. The major physical methods for this investigation are saturation transfer electron paramagnetic resonance (EPR) spectroscopy and spin-label induced nuclear relaxation technique. Conventional EPR and 31P nuclear magnetic resonance will also be used. Band 3 protein of the erythrocyte membranes is chosen for the pilot study. Several systems will be studied in terms of increasing complexity in order to understand the intrinsic properties of Band 3 protein and its interactions with lipids, other membrane proteins and permeants.